The present invention pertains to an exhaust elbow with a single exhaust outlet with an outlet mounting flange and at least two exhaust inlets with inlet mounting flanges for fastening on the engine block of a motor vehicle.
Exhaust elbows of the above-described type are formed according to the state of the art by a collector pipe, which has inlet pipe sections depending on the number of engine cylinders to be connected and an outlet pipe section, which is connected to downstream components of the exhaust system, e.g., a catalytic converter. The collector pipe may be a one-piece deep-drawn sheet metal part or be composed of individual pipes and particularly welded together.
Collector pipes manufactured according to the half shell technique have also been known, which are connected to one another by a longitudinal rebate. The collector pipe may be designed as a single-walled or double-walled pipe, i.e., with an air gap insulation, e.g., according to DE 199 52 648.
The basic object of the present invention is to provide an exhaust elbow of the above mentioned type, which has an extremely simple design and is nevertheless able to function.
According to the invention, an exhaust elbow is provided with a single exhaust outlet with an outlet mounting flange and at least two exhaust inlets with an inlet mounting flange for fastening on the engine block of a motor vehicle. The essence of the present invention is that the exhaust gas guiding of the exhaust elbow between the inlet mounting flange and the outlet mounting flange is formed by a single-walled sheet metal hood forming wherein the sheet metal hood surrounds all exhaust inlets together.
The sheet metal hood may comprise a radial flange closed on the circumference on the side of the exhaust outlet or a radial expansion, which flange or expansion is firmly connected to the outlet mounting flange in a gastight manner preferably by welding.
The sheet metal hood may correspondingly have an enveloping radial flange surrounding all exhaust inlets on the side of the exhaust inlets or a common enveloping radial expansion, which flange or expansion is firmly connected to the inlet mounting flange in a gastight manner preferably by welding.
The sheet metal hood has, in particular, shape-stabilizing indentations and/or bulges, where the indentations are preferably located in the area between the exhaust inlets.
In an especially simple variant of the present invention, the sheet metal hood is made in one piece. It may be bent from a flat sheet metal plate as a semi-finished part around a mandrel or the like into its complex final shape.
However, the sheet metal hood may also comprise, as an alternative, two half shells made from a sheet metal, which are connected to one another by means of a congruent connection flange.
The connection flange may be a gastight sheet metal rebate bent over at least once.
The two half shells may be mirror symmetrically identical in relation to the connection plane of the connection flanges.
The inlet mounting flange and the outlet mounting flange are preferably fastening plates arranged at right angles to one another with through holes for fastening on the engine block by means of studs.
Consequently, an exhaust elbow with a single outer shell in the form of a sheet metal hood, which covers the cylinder outlet opening on mounting on the engine block of the motor vehicle without forming an individual pipe itself, is proposed according to the present invention. The sheet metal hood or outer shell is single-walled. The exhaust elbow of the type according to the present invention is a very simple sheet metal elbow and can be called a so-called xe2x80x9cprimitive elbow,xe2x80x9d which is nevertheless sufficiently functional and collects the exhaust gases of the different outlet channels at the cylinder head and passes them into a discharge pipe. Considerable weight and considerable amounts of material are saved. The manufacturing costs are low. A downstream catalytic converter shows improved response behavior because of the reduced mass of the exhaust elbow. The exhaust elbow according to the present invention is suitable for all spark ignition and diesel engines and can be used in a versatile manner. It can be manufactured in an especially cost-effective manner in a large lot. The complex final shape of the sheet metal shell can be determined experimentally with respect to a favorable flow behavior, for minimizing noise, high dimensional stability and sufficient thermal loadability on a given engine unit with a certain output. Even though the sheet metal shell bent or shaped into the final shape does not have a particularly high dimensional stability in itself, the dimensional stability is obtained when the sheet metal shell is firmly welded or otherwise connected to the additionally stabilizing end flanges, e.g., by bonding or Tox clinching. A longitudinal rebate in the case of two-part half shells as a sheet metal shell leads to a further increase in the dimensional stability, as do reinforcing ribs, indentations, bulges and the like, especially the bent-up welded edges in the area of the end flanges.
The present invention will be explained in greater detail below on the basis of an exemplary embodiment with reference to the drawing attached.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawing and descriptive matter in which a preferred embodiment of the invention is illustrated.